The HNF1A gene p.I27L TT/GT genotype was associated with a greater risk of GDM in comparison with the GG genotype in co-dominant, dominant, and recessive models (dominant: GT + TT vs. GG-wild, 79.4 vs. 65.5%, OR = 2.02, 95% CI [1.21–3.38], p = 0.007 and recessive: TT vs. GT + GG, 20.6 vs. 11.7%, OR = 1.95, 95% CI [1.13–3.49], p = 0.036) (Table 3). Here, HNF1A is linked to gestational diabetes.